Samsung has released Android 2.3.6 update for Galaxy Ace S5830I in India. The update is available via Samsung Kies.

The new version is S5830IXXLA2/S5830IODDLA1.

you might receive notification of this update on your device, if you have received such a notification- follow the onscreen instructions and update with the same.

If you have not received any such, then you can check it manually. To do that follow the path of home screen and hit Menu > Settings > About Phone > System update and click on Android update. Your update will be automatically be installed on your handset and you would be able to use your handset within 10 minutes.